Here is a fun example of a really long sentence, though not a run-on since it is all connected phrases:

DEATH SENTENCE
Have you heard how Cuthbert Hatch
To find a gas leak struck a match
And thereby hastened his dispatch
To realms unknown to you and me
Who have not yet been foolishly
Inclined to leave posterity
To puzzle for itself just why

This spelling website is the best we have found: systematic, graded lists, quick online quizzes with no distractions. Look at the word, listen to it and spell it. In one hour a kid can quickly review an entire grade level of spelling words if they are a fast typist. Or spend 5 minutes a day to stay a super speller.

Making the best use of the morning commute is a challenge, when kids are still sleepy and not ready for anything too challenging. One possibility is to play an audio snippet. To play in the car without wifi, save the file ahead of time by right-clicking on the link to the .mp3 and choosing 'Save link as...' or similar.

Note this is the Houghton Mifflin Harcourt publisher's site, but is one of the better/most complete free resources I've found yet for grammar. The other resources on the site are so-so, so far as I've seen.